This application relates generally to pump systems, and more specifically, to a method and system for physiologic control of blood pumps.
Generally, blood pump systems are employed in either of two circumstances. First a blood pump may completely replace a human heart that is not functioning properly, or second, a blood pump may boost blood circulation in patients whose heart is still functioning although pumping at an inadequate rate. The blood pump may be external, partially implanted or completely implanted.
For example, U.S. Pat. No. 6,183,412, which is commonly assigned and incorporated herein by reference in its entirety, discloses a ventricle assist device (VAD) commercially referred to as the “DeBakey VAD®.” The VAD is a miniaturized continuous axial-flow pump designed to provide additional blood flow to patients who suffer from heart disease. The device is attached between the apex of the left ventricle and the aorta.
Known blood pump systems typically are controlled in an open loop fashion where a predetermined speed is set and the flow rate varies according to the pressure differential across the pump. The pump itself may be controlled in a closed loop fashion, wherein the actual pump speed is fed back to a motor controller that compares the actual speed to the desired predetermined speed proportional to some measured physiologic parameter and adjusts the pump accordingly. However, prior art devices using closed loop control systems which vary the pump speed in response to a monitored physiologic or pump parameter have largely been unsatisfactory.
The present invention addresses shortcomings associated with the prior art.